How do I prepare in one month for engineering placements and interviews?

When Army officers do commando course they realise that for those 45 days they saw NO Limit to stretching their minds to plan , execute & win the most complex operations in combat. They also learn , remember & apply that knowledge, give difficult exams & get above 60%. Many procure above 65% some even get above 75%.
So think that you are on a Commando Course.
Allot 16 to 18 hrs x 50 days = 800 hrs to 900 hrs to best work. Take help from parents, siblings , Mentors & real friends
You will win !